Invalid thread acces Execption

For my application I have created a menu in the system tray. When you click left you get some dynamic data and when you click right on my menu you get a screen to add a new dynamic menuitem to my system tray menu. but when I try to add something to that menu I get this error:

When you run this, you see a nice menu in the system tray..
add some text in the screen that popup and click on save.. now you see the error.. (In this example ill try to change the static menu into a dynamic one)